In the past, assemblies upon which motor driven and motorless vehicles and other equipment have been placed for washing debris from the exterior thereof have experienced problems and suffer disadvantages, among which are: (1) are complex and difficult to assemble and disassemble; (2) are not unitarily portable from location-to-location; (3) do not discharge substantially all of the removed debris from the washing site resulting in clogging of the assembly and down time to unclog; (4) do not efficiently remove, contain and control substantially all of the separated debris and all of the used wash liquid to a site remote from the washing site; (5) are labor intensive in assembling and disassembling; (6) do not allow continued washing while earlier removed and contained debris is loaded and transported to land fill or other disposal sites; (7) do not accommodate modular enlargement; (8) do not, in an effective and simplified way, segregate spent wash liquid for reused from removed and contained solid debris destined for land fill or other storage; (9) do not use only influent wash liquid to remove from the assembly substantially all debris displaced on the assembly at the washing site during the vehicle washing phase; and (10) do not provide for automated processing of contained spent wash liquid and removed and contained debris.